In news that probably has the White House on edge, Retired General Michael Flynn has pleaded guilty to one count of violating Title 18, United State Code, Section 1001(a)(2). Basically, that means he lied to the FBI about conversations with Russian Ambassador Sergey Kislyak that took place during the transition period between the Obama and Trump presidencies.

Retired Lt. Gen. Michael Flynn, once a member of President Donald Trump’s inner circle of advisers, pleaded guilty Friday to lying to the FBI about back-channel conversations with the Russian ambassador as part of a deal with the Special Counsel investigating foreign meddling in the 2016 elections.

Flynn’s plea signals the former top adviser to Trump is now cooperating with Special Counsel Robert Mueller’s team. A brief statement released by Mueller’s team Friday morning does not say what information Flynn has provided the government as part of the deal, but people familiar with the agreement told ABC News Friday he has made a decision to assist investigators.

The general told confidants about his decision to plead guilty in the last 24 hours, according to people close to Flynn, who say the former adviser feels Trump has abandoned him and has agreed to answer questions about the president or anyone else.

The question, of course, is what Flynn knows that Mueller wants. Over at Fox News, Judge Andrew Napolitano points out that Flynn could have been facing up to 60 years in prison, had Mueller thrown the book at him. As it is, he faces no more than 12 months. So, one would assume that Flynn has offered something fairly substantial to get such a huge reduction.

Obviously, this is un-sourced, so you should take it with a grain of salt. Other outlets are reporting that the contacts were only ordered during the transition - and possibly not by Trump - an important distinction. If everything occurred during the transition, there's probably nothing much to see here. If it happened during the campaign, that's another story.

The fact is we don't really know what Flynn is giving Mueller, and we probably won't know it for a few days. Even if he does testify against the President, he'll still need some way to prove what he's saying, or we'll just be in an endless "your word against mine" loop.